Zoom lens system, interchangeable lens apparatus and camera system

ABSTRACT

A zoom lens system is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit. The zoom lens system according to the present invention, in order from an object side to an image side, comprises: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having negative optical power; and at least one subsequent lens unit, wherein at the time of zooming, all lens units move in a direction along the optical axis so that intervals between the lens units vary, and at the time of focusing, a lens unit included in the at least one lens unit moves in a direction along the optical axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens system and, in particular,to a zoom lens system suitable for an imaging lens system employed in aninterchangeable lens apparatus in a so-called interchangeable-lens typedigital camera system (simply referred to as a “camera system”, in somecases hereinafter). Further, the present invention relates to aninterchangeable lens apparatus and a camera system that employ this zoomlens system.

2. Description of the Background Art

The market is rapidly growing for interchangeable-lens type digitalcamera systems each including: a camera body employing an image sensorcomposed of a CCD (Charge Coupled Device), a CMOS (ComplementaryMetal-Oxide Semiconductor) or the like; and an interchangeable lensapparatus employing an imaging lens system for forming an optical imageon the light acceptance surface of the image sensor, wherein the imaginglens system is attachable to and detachable from the camera body. As forthe interchangeable lens apparatuses, those employing a zoom lens systemcapable of forming an optical image with variable magnification arewidely favored.

Among zoom lens systems, in particular, telephoto-oriented zoom lenssystems have a long focal length at a telephoto limit, and hence oftenhave a long overall optical length (a distance from the top of the lenssurface on the most object side to the image surface). Thus, aconfiguration is often employed wherein a lens unit having positiveoptical power is arranged on the most object side and a lens unit havingnegative optical power is arranged on the most image side so that theoverall optical length at a telephoto limit is made shorter than thefocal length at a telephoto limit.

In telephoto-oriented zoom lens systems, configurations have beenproposed wherein the number of lens units is increased for the purposeof reducing various kinds of aberration. For example, a zoom lens systemconsisting of five lens units of positive, negative, negative, positiveand negative has been proposed (e.g., Japanese Patent Publication No.3134448 (Reference 1)). Further, in telephoto-oriented zoom lenssystems, the long focal length at a telephoto limit easily enhancesimage blur in association with vibration. Thus, methods have beenproposed that a part of lens units (an image blur compensation lensunit) is parallel-displaced in a direction perpendicular to the opticalaxis in accordance with a change in the orientation of the entire lenssystem (e.g., Japanese Laid-Open Patent Publication No. H6-123836(Reference 2), Japanese Patent Publication No. 3395169 (Reference 3),Japanese Laid-Open Patent Publication No. H6-130330 (Reference 4) andJapanese Laid-Open Patent Publication No. H11-202201 (Reference 5)

Each of the telephoto zoom lens systems described in References 2, 3,and 4 consists of five lens units of positive, negative, negative,positive and negative in order from the object side to the image side.The telephoto zoom lens system described in Reference 5 consists of fivelens units of positive, negative, negative, positive and negative oralternatively positive, negative, positive, positive and negative inorder from the object side to the image side. In each telephoto zoomlens system, one of the five lens units is parallel-displaced in adirection perpendicular to the optical axis so that image blurcompensation is achieved. When the individual lens units are referred toas the first lens unit, the second lens unit, . . . , and the fifth lensunit in order from the object side to the image side, the third lensunit in the telephoto zoom lens system described in Reference 2 isparallel-displaced in a direction perpendicular to the optical axis.Similarly, the second lens unit in the telephoto zoom lens systemdescribed in Reference 3, the fourth lens unit of the telephoto zoomlens system described in Reference 4, and a part of the second lens unitof the telephoto zoom lens system described in Reference 5 areparallel-displaced in a direction perpendicular to the optical axis.

In focusing in a telephoto zoom lens, a method of moving the first lensunit located on the most object side has widely been employed.Nevertheless, this focusing method based on the movement of the firstlens unit causes a problem in that high-speed auto-focusing cannot beachieved because of the largeness and heaviness of the first lens unit.For the purpose of resolving this problem, in the telephoto zoom lenssystem described in Reference 5, focusing from an infinite distance to aclose distance is proposed to be achieved by moving the fourth lens unitin an optical axis direction.

In interchangeable-lens type digital camera systems, video image takingis also desired in addition to still image taking. However, in videoimage taking, auto-focusing needs to be performed continuously at a highspeed.

In order that auto-focusing should be performed continuously at a highspeed, for example, a method of repeating a series of the followingoperations: oscillating (wobbling) a part of lens units in the opticalaxis directions at a high speed so that a situation of “out-of-focusstate→in-focus state→out-of-focus state” is obtained; detecting, fromthe output signal of the image sensor, signal components in apredetermined frequency band in a part of the image region so that anoptimal position realizing the in-focus state is calculated for thefocusing lens unit; and moving the focusing lens unit to the optimalposition, may be adopted. In order that uneasiness such as flickersshould be avoided, video displaying need be performed at a high rate of,for example, 30 frames per second. Thus, basically, image taking alsoneed be performed at the same rate of 30 frames per second. Accordingly,in auto-focusing in video image taking, the focusing lens unit need bewobbled continuously at the high rate of 30 Hz.

When the above-mentioned wobbling is to be employed, it should be notedthat the size of the image corresponding to a photographic object variesin association with wobbling. This variation is caused mainly by thefact that the movement of the focusing lens unit in the optical axisdirections generates a change in the focal length of the entire lenssystem. Then, when a large change in the image taking magnification isgenerated in association with wobbling, uneasiness is caused.

When the above-mentioned facts are taken into consideration, in orderthat the outer diameter of the lens barrel should be reduced, the weightof the image blur compensation lens unit and the focusing lens unit needbe reduced as light as possible. For this purpose, the outer diametersof the individual lens elements that constitute the image blurcompensation lens unit and the focusing lens unit need be reduced assmall as possible so that the weight of the individual lens units needbe reduced as light as possible. In this view, the techniques in theabove-mentioned references have problems individually.

For example, References 1 to 4 do not mention image blur compensation.Further, in the zoom lens system described in Reference 5, the fourthlens unit that moves at the time of focusing is also composed of threeor four lens elements. Thus, the fourth lens unit is heavy. This causesa problem that a larger motor or actuator for moving the fourth lensunit is required.

SUMMARY OF THE INVENTION

The present invention has been devised in view of the above-mentionedproblems. An object of the present invention is to provide: a zoom lenssystem having an image blur compensation function, satisfactory imagingcharacteristics, and a compact construction; and a camera systememploying this zoom lens system.

The zoom lens system according to the present invention, in order froman object side to an image side, comprises: a first lens unit havingpositive optical power; a second lens unit having negative opticalpower; a third lens unit having negative optical power; and at least onesubsequent lens unit. At the time of zooming, all lens units move in adirection along the optical axis so that intervals between the lensunits vary. At the time of focusing, a lens unit included in the atleast one lens unit moves in a direction along the optical axis.

The interchangeable lens apparatus according to the present inventioncomprises: a zoom lens system described above; and a camera mountsection connected to a camera body provided with an image sensor forreceiving an optical image formed by the zoom lens system and thenconverting the optical image into an electric image signal.

The camera system according to the present invention comprises: aninterchangeable lens apparatus that includes the zoom lens systemdescribed above; and a camera body that is connected to theinterchangeable lens apparatus via a camera mount section in anattachable and detachable manner and that includes an image sensor forreceiving an optical image formed by the zoom lens system and thenconverting the optical image into an electric image signal.

According to the present invention, a zoom lens system can be providedthat includes a compactly constructed focusing lens unit and that has asuppressed change in the image magnification at the time of movement ofa focusing lens unit; and an interchangeable lens apparatus and a camerasystem that employ this zoom lens system.

These and other objects, features, aspects and effects of the presentinvention will become clearer on the basis of the following detaileddescription with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 1 (Example 1);

FIG. 2 is a longitudinal aberration diagram showing an infinity in-focuscondition of a zoom lens system according to Example 1;

FIG. 3 is a longitudinal aberration diagram showing a close-pointin-focus condition of a zoom lens system according to Example 1;

FIG. 4 is a lateral aberration diagram in a basic state where image blurcompensation is not performed and in an image blur compensation state ata telephoto limit of a zoom lens system according to Example 1;

FIG. 5 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 2 (Example 2);

FIG. 6 is a longitudinal aberration diagram showing an infinity in-focuscondition of a zoom lens system according to Example 2;

FIG. 7 is a longitudinal aberration diagram showing a close-pointin-focus condition of a zoom lens system according to Example 2;

FIG. 8 is a lateral aberration diagram in a basic state where image blurcompensation is not performed and in an image blur compensation state ata telephoto limit of a zoom lens system according to Example 2;

FIG. 9 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 3 (Example 3);

FIG. 10 is a longitudinal aberration diagram showing an infinityin-focus condition of a zoom lens system according to Example 3;

FIG. 11 is a longitudinal aberration diagram showing a close-pointin-focus condition of a zoom lens system according to Example 3;

FIG. 12 is a lateral aberration diagram in a basic state where imageblur compensation is not performed and in an image blur compensationstate at a telephoto limit of a zoom lens system according to Example 3;

FIG. 13 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 4 (Example 4);

FIG. 14 is a longitudinal aberration diagram showing an infinityin-focus condition of a zoom lens system according to Example 4;

FIG. 15 is a longitudinal aberration diagram showing a close-pointin-focus condition of a zoom lens system according to Example 4;

FIG. 16 is a lateral aberration diagram in a basic state where imageblur compensation is not performed and in an image blur compensationstate at a telephoto limit of a zoom lens system according to Example 4;

FIG. 17 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 5 (Example 5);

FIG. 18 is a longitudinal aberration diagram showing an infinityin-focus condition of a zoom lens system according to Example 5;

FIG. 19 is a longitudinal aberration diagram showing a close-pointin-focus condition of a zoom lens system according to Example 5;

FIG. 20 is a lateral aberration diagram in a basic state where imageblur compensation is not performed and in an image blur compensationstate at a telephoto limit of a zoom lens system according to Example 5;and

FIG. 21 is a block diagram of a camera system according to Embodiment 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Each of FIGS. 1, 5, 9, 13 and 17 shows a zoom lens system in an infinityin-focus condition.

In each Fig., part (a) shows a lens configuration at a wide-angle limit(in the minimum focal length condition: focal length f_(W)), part (b)shows a lens configuration at a middle position (in an intermediatefocal length condition: focal length f_(M)=√{square root over((f_(W)·f_(T)))}, and part (c) shows a lens configuration at a telephotolimit (in the maximum focal length condition: focal length f_(T)).Further, in each Fig., each bent arrow located between part (a) and part(b) indicates a line obtained by connecting the positions of each lensunit respectively at a wide-angle limit, a middle position and atelephoto limit. In the part between the wide-angle limit and the middleposition and the part between the middle position and the telephotolimit, the positions are connected simply with a straight line, andhence this line does not indicate actual motion of each lens unit.Moreover, in each Fig., an arrow imparted to a lens unit indicatesfocusing from an infinity in-focus condition to a close-object in-focuscondition. That is, the arrow indicates the moving direction at the timeof focusing from an infinity in-focus condition to a close-objectin-focus condition.

Further, in FIGS. 1, 5, 9, 13 and 17, an asterisk “*” imparted to aparticular surface indicates that the surface is aspheric. In each Fig.,symbol (+) or (−) imparted to the symbol of each lens unit correspondsto the sign of the optical power of the lens unit. Further, in eachFig., the straight line located on the most right-hand side indicatesthe position of the image surface S.

Embodiment 1

The zoom lens system according to Embodiment 1, in order from the objectside to the image side, comprises a first lens unit G1 having positiveoptical power, a second lens unit G2 having negative optical power, athird lens unit G3 having negative optical power, a fourth lens unit G4having positive optical power, a 5A-th lens unit G5A having negativeoptical power, and a 5B-th lens unit G5B having positive optical power.

The first lens unit G1, in order from the object side to the image side,comprises: a negative meniscus first lens element L1 with the convexsurface facing the object side; a bi-convex second lens element L2; anda positive meniscus third lens element L3 with the convex surface facingthe object side. The first lens element L1 and the second lens elementL2 are cemented with each other.

The second lens unit G2, in order from the object side to the imageside, comprises: a negative meniscus fourth lens element L4 with theconvex surface facing the object side; and a positive meniscus fifthlens element L5 with the convex surface facing the object side.

The third lens unit G3 comprises: a bi-concave sixth lens element L6;and a positive meniscus seventh lens element L7 with the convex surfacefacing the object side.

The fourth lens unit G4 comprises: a positive meniscus eighth lenselement L8 with the concave surface facing the object side; a bi-convexninth lens element L9; a negative meniscus tenth lens element L10 withthe convex surface facing the object side; a bi-convex eleventh lenselement L11; a bi-convex twelfth lens element L12; and a negativemeniscus thirteenth lens element L13 with the concave surface facing theobject side. The tenth lens element L10 and the eleventh lens elementL11 are cemented with each other. Further, the twelfth lens element L12and the thirteenth lens element L13 are cemented with each other.

The 5A-th lens unit G5A is composed of a negative meniscus fourteenthlens element L14 with the concave surface facing the image side.

The 5B-th lens unit G5B comprises: a bi-convex fifteenth lens elementL15; and a negative meniscus sixteenth lens element L16 with the convexsurface facing the object side.

At the time of zooming from a wide-angle limit to a telephoto limit, theindividual lens units move in a direction along the optical axis.

An aperture diaphragm A is arranged between the third lens unit G3 andthe fourth lens unit G4, and moves together with the third lens unit G3.

Further, at the time of focusing from an infinity in-focus condition toa close-point in-focus condition, the 5A-th lens unit G5A moves to theimage side along the optical axis.

Further, for the purpose of compensation of image blur caused byvibration applied to the entire system, the third lens unit G3 moves ina direction perpendicular to the optical axis.

Here, the planar plate L17 arranged on the most image side correspondsto a low-pass filter or a face plate.

Embodiment 2

The zoom lens system according to Embodiment 2, in order from the objectside to the image side, comprises a first lens unit G1 having positiveoptical power, a second lens unit G2 having negative optical power, athird lens unit G3 having negative optical power, a fourth lens unit G4having positive optical power, 5A-th lens unit G5A having negativeoptical power, and a 5B-th lens unit G5B having positive optical power.

The first lens unit G1, in order from the object side to the image side,comprises: a negative meniscus first lens element L1 with the convexsurface facing the object side; a bi-convex second lens element L2; anda positive meniscus third lens element L3 with the convex surface facingthe object side. The first lens element L1 and the second lens elementL2 are cemented with each other.

The second lens unit G2, in order from the object side to the imageside, comprises a bi-concave fourth lens element L4 and a bi-convexfifth lens element L5.

The third lens unit G3 comprises: a bi-concave sixth lens element L6;and a positive meniscus seventh lens element L7 with the convex surfacefacing the object side.

The fourth lens unit G4 comprises: a positive meniscus eighth lenselement L8 with the concave surface facing the object side; a bi-convexninth lens element L9; a negative meniscus tenth lens element L10 withthe convex surface facing the object side; a bi-convex eleventh lenselement L11; and a bi-convex twelfth lens element L12.

The 5A-th lens unit G5A is composed of a bi-concave thirteenth lenselement L13.

The 5B-th lens unit G5B is composed of a positive meniscus fourteenthlens element L14 with the convex surface facing the object side.

At the time of zooming from a wide-angle limit to a telephoto limit, theindividual lens units move in a direction along the optical axis.

An aperture diaphragm A is arranged between the third lens unit G3 andthe fourth lens unit G4, and moves together with the third lens unit G3.

Further, at the time of focusing from an infinity in-focus condition toa close-point in-focus condition, the 5A-th lens unit G5A moves to theimage side along the optical axis.

Further, for the purpose of compensation of image blur caused byvibration applied to the entire system, the third lens unit G3 moves ina direction perpendicular to the optical axis.

Here, the planar plate L15 arranged on the most image side correspondsto a low-pass filter or a face plate.

Embodiment 3

The zoom lens system according to Embodiment 3, in order from the objectside to the image side, comprises a first lens unit G1 having positiveoptical power, a second lens unit G2 having negative optical power, athird lens unit G3 having negative optical power, a fourth lens unit G4having positive optical power, and a fifth lens unit G5 having negativeoptical power.

The first lens unit G1, in order from the object side to the image side,comprises: a negative meniscus first lens element L1 with the convexsurface facing the object side; a bi-convex second lens element L2; anda positive meniscus third lens element L3 with the convex surface facingthe object side. The first lens element L1 and the second lens elementL2 are cemented with each other.

The second lens unit G2, in order from the object side to the imageside, comprises: a negative meniscus fourth lens element L4 with theconvex surface facing the object side; and a bi-convex fifth lenselement L5.

The third lens unit G3 comprises: a bi-concave sixth lens element L6;and a positive meniscus seventh lens element L7 with the convex surfacefacing the object side.

The fourth lens unit G4 comprises: a positive meniscus eighth lenselement L8 with the concave surface facing the object side; a bi-convexninth lens element L9; a negative meniscus tenth lens element L10 withthe convex surface facing the object side; a bi-convex eleventh lenselement L11; and a bi-convex twelfth lens element L12.

The fifth lens unit G5 comprises: a bi-concave thirteenth lens elementL13; and a positive meniscus fourteenth lens element L14 with the convexsurface facing the object side.

At the time of zooming from a wide-angle limit to a telephoto limit, theindividual lens units move in a direction along the optical axis.

An aperture diaphragm A is arranged between the third lens unit G3 andthe fourth lens unit G4, and moves together with the third lens unit G3.

Further, at the time of focusing from an infinity in-focus condition toa close-point in-focus condition, the fifth lens unit G5 moves to theimage side along the optical axis.

Further, for the purpose of compensation of image blur caused byvibration applied to the entire system, the third lens unit G3 moves ina direction perpendicular to the optical axis.

Here, the planar plate L15 arranged on the most image side correspondsto a low-pass filter or a face plate.

Embodiment 4

The zoom lens system according to Embodiment 4, in order from the objectside to the image side, comprises a first lens unit G1 having positiveoptical power, a second lens unit G2 having negative optical power, athird lens unit G3 having negative optical power, a fourth lens unit G4having positive optical power, a 5A-th lens unit G5A having positiveoptical power, and a 5B-th lens unit G5B having negative optical power.

The first lens unit G1, in order from the object side to the image side,comprises: a negative meniscus first lens element L1 with the convexsurface facing the object side; a positive meniscus second lens elementL2 with the convex surface facing the object side; and a positivemeniscus third lens element L3 with the convex surface facing the objectside. The first lens element L1 and the second lens element L2 arecemented with each other.

The second lens unit G2, in order from the object side to the imageside, comprises a bi-concave fourth lens element L4 and a bi-convexfifth lens element L5.

The third lens unit G3 comprises: a bi-concave sixth lens element L6;and a positive meniscus seventh lens element L7 with the convex surfacefacing the object side. The sixth lens element L6 and the seventh lenselement L7 are cemented with each other.

The fourth lens unit G4 comprises: a bi-convex eighth lens element L8; abi-convex ninth lens element L9; and a negative meniscus tenth lenselement L10 with the concave surface facing the object side. The ninthlens element L9 and the tenth lens element L10 are cemented with eachother.

The 5A-th lens unit G5A comprises: a positive meniscus eleventh lenselement L11 with the concave surface facing the object side; and abi-convex twelfth lens element L12.

The 5B-th lens unit G5B is composed of a negative meniscus thirteenthlens element L13 with the convex surface facing the object side.

At the time of zooming from a wide-angle limit to a telephoto limit, theindividual lens units move in a direction along the optical axis.

An aperture diaphragm A is arranged between the third lens unit G3 andthe fourth lens unit G4, and moves together with the third lens unit G3.

Further, at the time of focusing from an infinity in-focus condition toa close-point in-focus condition, the 5A-th lens unit GSA moves to theobject side along the optical axis.

Further, for the purpose of compensation of image blur caused byvibration applied to the entire system, the third lens unit G3 moves ina direction perpendicular to the optical axis.

Here, the planar plate L14 arranged on the most image side correspondsto a low-pass filter or a face plate.

Embodiment 5

The zoom lens system according to Embodiment 5, in order from the objectside to the image side, comprises a first lens unit G1 having positiveoptical power, a second lens unit G2 having negative optical power, athird lens unit G3 having negative optical power, a fourth lens unit G4having positive optical power, a 5A-th lens unit G5A having negativeoptical power, and a 5B-th lens unit G5B having negative optical power.

The first lens unit G1, in order from the object side to the image side,comprises: a negative meniscus first lens element L1 with the convexsurface facing the object side; a bi-convex second lens element L2; anda positive meniscus third lens element L3 with the convex surface facingthe object side. The first lens element L1 and the second lens elementL2 are cemented with each other.

The second lens unit G2, in order from the object side to the imageside, comprises: a fourth lens element L4 with the convex surface facingthe object side; a bi-concave fifth lens element L5; and a positivemeniscus sixth lens element L6 with the convex surface facing the objectside.

The third lens unit G3, in order from the object side to the image side,comprises: a positive meniscus seventh lens element L7 with the concavesurface facing the object side; a bi-concave eighth lens element L8; anda positive meniscus ninth lens element L9 with the convex surface facingthe object side. The eighth lens element L8 and the ninth lens elementL9 are cemented with each other.

The fourth lens unit G4, in order from the object side to the imageside, comprises: a bi-convex tenth lens element L10; a bi-convexeleventh lens element L11; a bi-concave twelfth lens element L12; abi-convex thirteenth lens element L13; a negative meniscus fourteenthlens element L14 with the convex surface facing the object side; and abi-convex fifteenth lens element L15. The fourteenth lens element L14and the fifteenth lens element L15 are cemented with each other.

The 5A-th lens unit G5A, in order from the object side to the imageside, comprises: a positive meniscus sixteenth lens element L16 with theconcave surface facing the object side; and a bi-concave seventeenthlens element L17 with the convex surface facing the image side. Thesixteenth lens element L16 and the seventeenth lens element L17 arecemented with each other.

The 5B-th lens unit G5B, in order from the object side to the imageside, comprises: a bi-convex eighteenth lens element L18; a negativemeniscus nineteenth lens element L19 with the convex surface facing theimage side; and a positive meniscus twentieth lens element L20 with theconvex surface facing the object side.

At the time of zooming from a wide-angle limit to a telephoto limit, theindividual lens units move in a direction along the optical axis.

An aperture diaphragm A is arranged between the third lens unit G3 andthe fourth lens unit G4, and moves together with the fourth lens unitG4.

Further, at the time of focusing from an infinity in-focus condition toa close-point in-focus condition, the fifth lens unit G5 moves to theimage side along the optical axis.

Further, for the purpose of compensation of image blur caused byvibration applied to the entire system, the third lens unit G3 moves ina direction perpendicular to the optical axis.

Here, the planar plate L21 arranged on the most image side correspondsto a low-pass filter or a face plate.

The following description is given for conditions to be satisfied by thezoom lens system according to each embodiment. Here, in the zoom lenssystem according to each embodiment, a plurality of conditions to besatisfied are set forth. Thus, a configuration of a zoom lens systemthat satisfies as many applicable conditions as possible is mostpreferable. However, when an individual condition is satisfied, a zoomlens system having the corresponding effect can be obtained.

As in the zoom lens systems according to the individual embodiments,when the image blur compensation lens unit is located on the object siderelative to the focusing lens unit, it is preferable that the followingcondition is satisfied.0.3<|f _(F) /f _(of)|<6.0  (1)

where,

f_(F) is a focal length of the focusing lens unit, and

f_(of) is a composite focal length of the lens units located within arange from the image blur compensation lens unit to the focusing lensunit at a wide-angle limit.

The condition (1) relates to the focal lengths of the image blurcompensation lens unit and the focusing lens unit. When the valueexceeds the upper limit of the condition (1), the focal length of theimage blur compensation lens unit becomes excessively small. This causesdifficulty in compensating off-axial aberration generated in associationwith image blur compensation. Thus, this situation is unpreferable. Incontrast, when the value goes below the lower limit of the condition(1), the focal length of the focusing lens unit becomes short. At thesame time, aberration fluctuation at the time of focusing increases.This causes difficulty in compensation.

As in the zoom lens systems according to the individual embodiments,when the image blur compensation lens unit is located on the object siderelative to the focusing lens unit, it is preferable that the followingcondition is satisfied.0.5<|f _(o) /f _(W)|<2.8  (2)

(here, f_(T)/f_(W)>4)

where,

f_(o) is a focal length of the image blur compensation lens unit,

f_(T) is a focal length of the entire system at a telephoto limit, and

f_(W) is a focal length of the entire system at a wide-angle limit.

The condition (2) sets forth the focal length of the image blurcompensation lens unit. When the value exceeds the upper limit of thecondition (2), the focal length of the image blur compensation lens unitbecomes short. This causes difficulty in compensating, by the subsequentlens units, off-axial aberration fluctuation generated in associationwith image blur compensation. Thus, this situation is unpreferable. Incontrast, when the value goes below the lower limit of the condition(2), the focal length of the image blur compensation lens unit becomesexcessively long. Thus, the movement of lens units at the time of imageblur compensation becomes large. Accordingly, this situation isunpreferable.

In the zoom lens system according to each embodiment, it is preferablethat the following condition is satisfied.0.1<|f ₂ /f ₁<3.5  (3)

where,

f₁ is a focal length of the first lens unit, and

f₂ is a focal length of the second lens unit.

The condition (3) regulates a ratio of magnitude of a focal length ofthe second lens unit to magnitude of a focal length of the first lensunit to decrease overall length of the lens system at a telephoto limitand to compensate various aberrations in a balanced manner. When thevalue exceeds the upper limit of the condition (3), off-axial aberrationgenerated in the second lens unit becomes excessively large. This causesdifficulty in compensating the off-axial aberration by other lens units.In contrast, when the value goes below the lower limit of the condition(3), an axial distance between the second lens unit and the third lensunit becomes long or back focus becomes long. In either case, theoverall length of the lens system at telephoto limit becomes long. Here,the overall length of the lens system may be decreased by decreasing afocal length of the third lens unit. In this case, however, off-axialaberration generated in the third lens unit becomes excessively large,thereby causing difficulty in compensating the off-axial aberration bythe subsequent lens units.

Here, the individual lens units in each embodiment are composedexclusively of refractive type lens elements that deflect incident lightby refraction (that is, lens elements of a type in which deflection isachieved at the interface between media each having a distinctrefractive index). However, the present invention is not limited to thisconstruction. For example, the lens units may employ diffractive typelens elements that deflect the incident light by diffraction;refractive-diffractive hybrid type lens elements that deflect theincident light by a combination of diffraction and refraction; orgradient index type lens elements that deflect the incident light bydistribution of refractive index in the medium.

Embodiment 6

FIG. 21 is a block diagram of a camera system according to Embodiment 6.The camera system according to Embodiment 6 includes a camera body 100and an interchangeable lens apparatus 200.

The camera body 100 includes a camera controller 101, an image sensor102, a shutter unit 103, an image display controller 104, an imagesensor control section 105, a contrast detection section 106, a shuttercontrol section 107, an image recording control section 108, a display110, a release button 111, a memory 112, a power supply 113 and a cameramount 114.

The camera controller 101 is an arithmetic operation unit forcontrolling the entire camera system. The camera controller 101 iselectrically connected to the image display controller 104, the imagesensor control section 105, the contrast detection section 106, theshutter control section 107, the image recording control section 108,the memory 112 and the camera mount 114, and can exchange signals withthese sections. Further, the camera controller 101 is electricallyconnected to the release button 111, and receives a signal generated atthe time of operation of the release button 111. Moreover, the cameracontroller 101 is connected to the power supply 113.

The image sensor 102 is composed, for example, of a CMOS sensor. Theimage sensor 102 converts an optical image incident on the lightreceiving plane into image data, and then outputs the image data. Theimage sensor 102 is driven in accordance with a driving signal from theimage sensor control section 105. In response to a control signal fromthe camera controller 101, the image sensor control section 105 outputsa driving signal for driving the image sensor 102, and then outputs tothe camera controller 101 the image data outputted from the image sensor102. In response to a control signal from the camera controller 101, thecontrast detection section 106 calculates and detects the contrast ofthe image data outputted from the image sensor 102, and then outputs theresult to the camera controller 101.

The shutter unit 103 includes a shutter plate for shutting off theoptical path for the image light to be incident on the image sensor 102.The shutter unit 103 is driven in accordance with a driving signal fromthe shutter control section 107. In response to a control signal fromthe camera controller 101, the shutter control section 107 controls theopening or closing timing for the shutter plate of the shutter unit 103.

The display 110 is composed, for example, of a liquid crystal displayunit. The display 110 is driven in accordance with a driving signal fromthe image display controller 104 so as to display an image on thedisplay surface. In response to a control signal from the cameracontroller 101, the image display controller 104 outputs image data tobe displayed on the display 110 and a driving signal for driving thedisplay 110.

In response to a control signal from the camera controller 101, theimage recording control section 108 outputs image data to a memory card109 connected in an attachable and removable manner.

The camera mount 114 mechanically connects the camera body 100 to theinterchangeable lens apparatus 200 described later. Further, the cameramount 114 serves also as an interface for electrically connecting thecamera body 100 to the interchangeable lens apparatus 200 describedlater.

The interchangeable lens apparatus 200 includes a lens controller 201,an image blur control section 202, a diaphragm control section 203, afocus control section 204, a zoom control section 205, a memory 206, ablur detection section 207, a diaphragm unit 208, a zoom lens system 209(a zoom lens unit 209 a, a focusing lens unit 209 b and an image blurcompensation lens unit 209 c), and a lens mount 210.

The lens controller 201 is an arithmetic operation unit for controllingthe entirety of the interchangeable lens apparatus 200, and is connectedthrough the lens mount 210 and the camera mount 114 to the cameracontroller 101 in the camera body described above. The lens controller201 is electrically connected to the image blur control section 202, thediaphragm control section 203, the focus control section 204, the zoomcontrol section 205, the memory 206 and the blur detection section 207,and can exchange signals with these sections.

The zoom lens system 209 is a zoom lens system according to Embodiment 1described above. The zoom lens system 209 includes a zoom lens unit 209a, a focusing lens unit 209 b, and an image blur compensation lens unit209 c. Here, the classification of the zoom lens unit 209 a, thefocusing lens unit 209 b and the image blur compensation lens unit 209 cis merely conceptual and adopted for simplicity of description. Thus,this classification does not exactly describe the actual construction ofthe actual zoom lens system. In the zoom lens system 209, zooming isachieved when the zoom lens unit 209 a moves in a direction along theoptical axis. In the zoom lens system 209, focusing is achieved when thefocusing lens unit 209 b moves in a direction along the optical axis.Further, in the zoom lens system 209, image blur compensation isachieved when the image blur compensation lens unit 209 c moves in adirection perpendicular to the optical axis.

In response to a control signal from the lens controller 201, the imageblur control section 202 detects and outputs the present position of theimage blur compensation lens unit 209 c. Further, the image blur controlsection 202 outputs a driving signal for driving the image blurcompensation lens unit 209 c, so as to drive the image blur compensationlens unit 209 c in a direction perpendicular to the optical axis.

In response to a control signal from the lens controller 201, thediaphragm control section 203 detects and outputs the present positionof the diaphragm unit 208. Further, the diaphragm control section 203outputs a driving signal for driving the diaphragm blades provided inthe diaphragm unit 208, and thereby opens or closes the diaphragm so asto change the F-number of the optical system.

In response to a control signal from the lens controller 201, the focuscontrol section 204 detects and outputs the present position of thefocusing lens unit 209 b. Further, the focus control section 204 outputsa driving signal for driving focusing group 209 b, so as to drive thefocusing lens unit 209 b in a direction along the optical axis.

In response to a control signal from the lens controller 201, the zoomcontrol section 205 detects and outputs the present position of the zoomlens unit 209 a. Further, the zoom control section 205 outputs a drivingsignal for driving the zoom lens unit 209 a, so as to drive the zoomlens unit 209 a in a direction along the optical axis.

In the above-mentioned configuration, when the release button 111 ispressed half, the camera controller 101 executes a routine ofauto-focusing. First, the camera controller 101 communicates with thelens controller 201 via the camera mount 114 and the lens mount 210, soas to detect the state of the zoom lens unit 209 a, the focusing lensunit 209 b, the image blur compensation lens unit 209 c and thediaphragm unit 208.

Then, the camera controller 101 communicates with the lens controller201 via the camera mount 114 and the lens mount 210, so as to output tothe lens controller 201 a control signal for driving and wobbling thefocusing lens unit 209 b. In accordance with the control signal, thelens controller 201 controls the focus control section 204 so as todrive and wobble the focusing lens unit 209 b. At the same time, thecamera controller 101 communicates with the lens controller 201 via thecamera mount 114 and the lens mount 210, so as to output a controlsignal for instructing the lens controller 201 to adjust the aperturevalue into a predetermined value. In accordance with the control signal,the lens controller 201 controls the diaphragm control section 203 so asto drive the diaphragm blades of the diaphragm unit 208 incorrespondence to the predetermined F-number.

On the other hand, the camera controller 101 outputs a control signal tothe image sensor control section 105 and the contrast detection section106. The image sensor control section 105 and the contrast detectionsection 106 individually acquire an output from the image sensor 102 ina manner corresponding to the sampling frequency of the wobbling driveof the focusing lens unit 209 b. In accordance with the control signalfrom the camera controller 101, the image sensor control section 105transmits image data corresponding to the optical image to the cameracontroller 101. The camera controller 101 performs predetermined imageprocessing onto the image data, and then transmits the result to theimage display controller 104. The image display controller 104 displaysthe image data in the form of a visible image onto the display 110.

Further, the contrast detection section 106 calculates the contrastvalue of the image data in association with wobbling, and then transmitsthe result to the camera controller 101. On the basis of the detectionresult from the contrast detection section 106, the camera controller101 determines the direction of focusing movement and the amount ofmovement for the focusing lens unit, and then transmits the informationthereof to the lens controller 201. The lens controller 201 outputs acontrol signal to the focus control section 204 so as to move thefocusing lens unit 209 b. In accordance with the control signal from thelens controller 201, the focus control section 204 drives the focusinglens unit 209 b.

When auto-focusing is to be performed in a live view state, theabove-mentioned operation is repeated. When auto-focusing is to beperformed in a live view state, wobbling of the focusing lens unit 209 bis performed continuously. At that time, the zoom lens system accordingto each embodiment has merely a small image magnification change inassociation with wobbling, and has a light weight. Thus, an imaging lenssystem suitable for the above-mentioned system is obtained.

Embodiment 6 given above has been described for a case in which the zoomlens system according to Embodiment 1 is employed. However, obviously, azoom lens system according to another embodiment may be employed.

EXAMPLES

Numerical examples are described below in which the zoom lens systemsaccording to Embodiments 1 to 5 are implemented. As described later,Numerical Examples 1 to 5 correspond to Embodiments 1 to 5,respectively. In the numerical examples, the units of the length in thetables are all “mm”, while the units of the view angle are all “°”.Moreover, in the numerical examples, r is the radius of curvature, d isthe axial distance, nd is the refractive index to the d-line, and vd isthe Abbe number to the d-line. In the numerical examples, the surfacesmarked with “*” are aspheric surfaces, and the aspheric surfaceconfiguration is defined by the following expression.

$Z = {\frac{h^{2}/r}{1 + \sqrt{1 - {\left( {1 + \kappa} \right)\left( {h/r} \right)^{2}}}} + {\sum{A_{n}h^{n}}}}$

Here, the symbols in the formula indicate the following quantities.

Z is the distance from an on-the-aspheric-surface point at a height hrelative to the optical axis to a tangential plane at the top of theaspheric surface,

h is the height relative to the optical axis,

r is the radius of curvature at the top,

κ is the conic constant, and

An is the n-th order aspherical coefficient.

FIGS. 2, 6, 10, 14 and 18 are longitudinal aberration diagrams of aninfinity in-focus condition of the zoom lens systems according toNumerical Examples 1, 2, 3, 4 and 5.

FIGS. 3, 7, 11, 15 and 19 are longitudinal aberration diagrams of aclose-point in-focus condition of the zoom lens systems according toNumerical Examples 1, 2, 3, 4 and 5.

In each longitudinal aberration diagram, part (a) shows the aberrationat a wide-angle limit, part (b) shows the aberration at a middleposition, and part (c) shows the aberration at a telephoto limit. Eachlongitudinal aberration diagram, in order from the left-hand side, showsthe spherical aberration (SA (mm)), the astigmatism (AST (mm)) and thedistortion (DIS (%)) In each spherical aberration diagram, the verticalaxis indicates the F-number (in each Fig., indicated as F), and thesolid line, the short dash line and the long dash line indicate thecharacteristics to the d-line, the F-line and the C-line, respectively.In each astigmatism diagram, the vertical axis indicates the imageheight (in each Fig., indicated as H), and the solid line and the dashline indicate the characteristics to the sagittal image plane (in eachFig., indicated as “s”) and the meridional image plane (in each Fig.,indicated as “m”), respectively. In each distortion diagram, thevertical axis indicates the image height (in each Fig., indicated as H).

In each numerical example, as seen from the longitudinal aberrationdiagram of an infinity in-focus condition and the longitudinalaberration diagram of a close-point in-focus condition, also in aclose-point in-focus condition, each zoom lens system achievessatisfactory aberration performance similar to that in an infinityin-focus condition.

FIGS. 4, 8, 12, 16 and 20 are lateral aberration diagrams in a basicstate where image blur compensation is not performed and in an imageblur compensation state of a zoom lens system according to NumericalExamples 1, 2, 3, 4 and 5.

In each lateral aberration diagram, the aberration diagrams in the upperthree parts correspond to a basic state where image blur compensation isnot performed at a telephoto limit, while the aberration diagrams in thelower three parts correspond to an image blur compensation state wherethe image blur compensation lens unit moves by a predetermined amount ina direction perpendicular to the optical axis at a telephoto limit.Among the lateral aberration diagrams of a basic state, the upper partshows the lateral aberration at an image point of 75% of the maximumimage height, the middle part shows the lateral aberration at the axialimage point, and the lower part shows the lateral aberration at an imagepoint of −75% of the maximum image height. Among the lateral aberrationdiagrams of an image blur compensation state, the upper part shows thelateral aberration at an image point of 75% of the maximum image height,the middle part shows the lateral aberration at the axial image point,and the lower part shows the lateral aberration at an image point of−75% of the maximum image height. In each lateral aberration diagram,the horizontal axis indicates the distance from the principal ray on thepupil surface, and the solid line, the short dash line and the long dashline indicate the characteristics to the d-line, the F-line and theC-line, respectively. In each lateral aberration diagram, the meridionalimage plane is adopted as the plane containing the optical axis of thefirst lens unit G1.

Here, in the zoom lens system according to each numerical example, theamount (Y_(T)) of movement of the compensation lens unit in a directionperpendicular to the optical axis in an image blur compensation state ata telephoto limit is as follows.

TABLE 1 (amount of movement of compensation lens unit) Numerical ExampleY_(T) 1 0.43 2 0.43 3 0.31 4 0.45 5 0.44

As seen from the lateral aberration diagrams, in each zoom lens system,satisfactory symmetry is obtained in the lateral aberration at the axialimage point. Further, when the lateral aberration at the +75% imagepoint and the lateral aberration at the −75% image point are comparedwith each other in a basic state, all have a small degree of curvatureand almost the same inclination in the aberration curve. Thus,decentering coma aberration and decentering astigmatism are small. Thisindicates that satisfactory imaging performance is obtained even in animage blur compensation state. Further, when the image blur compensationangle of a zoom lens system is the same, the amount of paralleltranslation required for image blur compensation decreases withdecreasing focal length of the entire zoom lens system. Thus, atarbitrary zoom positions, satisfactory image blur compensation can beperformed without degrading the imaging characteristics.

Numerical Example 1

The zoom lens system of Numerical Example 1 corresponds to Embodiment 1shown in FIG. 1. The data of the zoom lens system according to NumericalExample 1 is shown in the following tables.

TABLE 2 (surface data) Surface number r d nd vd Object surface ∞Variable  1 79.88860 1.20000 1.84666 23.8  2 55.84100 4.38040 1.4970081.6  3 −538.09420 0.20000  4 40.97500 4.17440 1.48749 70.4  5 171.38530Variable  6 149.25700 0.80000 1.83400 37.3  7 19.24660 4.98360  831.30520 2.43820 1.84666 23.8  9 795.70900 Variable 10 −46.11980 0.799401.77250 49.6 11 37.65760 0.68440 12 22.26400 1.39710 1.92286 20.9 1326.59940 8.97180 14 (Aperture) ∞ Variable 15 −85.03340 1.80330 1.4970081.6 16 −35.73500 0.10050 17 165.76270 2.00390 1.49700 81.6 18 −69.043100.20000 19 54.65300 0.80000 1.92286 20.9 20 37.32040 2.79140 1.4970081.6 21 −93.02670 0.20000 22 33.57310 3.54500 1.49700 81.6 23 −37.217100.80220 1.88300 40.8 24 −94.83610 Variable 25 3674.43700 0.70110 1.7725049.6 26 23.16340 Variable 27 54.32140 2.27740 1.75520 27.5 28 −46.599600.10000 29 153.18810 0.80000 1.83481 42.7 30 25.42440 Variable 31 ∞4.20000 1.51680 64.2 32 ∞ BF Image surface ∞

TABLE 3-1 (various data) Zooming ratio 4.24425 Wide Middle TelephotoFocal length 41.2718 89.3913 193.4154 F number 3.59391 4.65880 6.26304View angle 15.0327 6.8445 3.1916 Image height 11.0300 11.0300 11.0300Overall length of 116.3210 129.8654 154.5799 lens system BF 0.991561.01132 0.99975 d0 ∞ ∞ ∞ d5 1.6530 22.7100 32.4306 d9 8.5027 3.47565.9904 d14 16.9073 8.9078 1.1313 d24 15.3069 10.4853 1.0412 d26 2.74263.3486 12.6422 d30 19.8628 29.5727 49.9904

TABLE 3-2 (various data) Wide Middle Telephoto Focal length 40.878586.3288 175.1678 F number 3.59488 4.66053 6.38448 View angle 15.05916.8432 3.1309 Image height 11.0300 11.0300 11.0300 Overall length of116.3339 129.8760 154.4691 lens system BF 1.01382 1.02127 0.89152 d03883.6791 3870.1455 3845.4204 d5 1.6530 22.7100 32.4306 d9 8.5027 3.47565.9904 d14 16.9073 8.9078 1.1313 d24 15.4706 11.0079 2.1911 d26 2.56962.8266 11.4897 d30 19.8628 29.5727 49.9904

Numerical Example 2

The zoom lens system of Numerical Example 2 corresponds to Embodiment 2shown in FIG. 5. The data of the zoom lens system according to NumericalExample 2 is shown in the following tables.

TABLE 4 (surface data) Surface number r d nd vd Object surface ∞Variable  1 96.08820 1.20030 1.84666 23.8  2 61.13150 4.96580 1.4970081.6  3 −233.55870 0.20000  4 47.75020 3.83530 1.48749 70.4  5 206.95980Variable  6 −107.60720 0.89610 1.88300 40.8  7 21.03400 0.25840  824.92220 2.49620 1.78470 26.1  9 −228.53650 Variable 10 −37.423600.90270 1.83481 42.7 11 27.11510 0.10000 12 24.16450 1.63050 1.9228620.9 13 55.10970 7.17610 14 (Aperture) ∞ Variable 15 −198.76890 2.196601.49700 81.6 16 −33.20810 0.18370 17 60.33330 2.29510 1.49700 81.6 18−114.41090 0.15780 19 170.03360 0.89890 1.84666 23.8 20 28.36260 0.2032021 29.80500 3.66370 1.49700 81.6 22 −61.71440 0.19890 23 32.385102.88520 1.58921 41.0 24 −215.78670 Variable 25* −696.90530 0.958001.69100 54.7 26* 18.48420 Variable 27 25.42090 1.63640 1.84666 23.8 2841.70670 Variable 29 ∞ 4.20000 1.51680 64.2 30 ∞ BF Image surface ∞

TABLE 5 (aspherical data) Surface No. Parameters 25 K = 0.00000E+00, A4= −1.34852E−05, A6 = 4.68839E−07, A8 = −4.71690E−09, A10 = 1.38874E−1126 K = 0.00000E+00, A4 = −2.58833E−05, A6 = 5.06789E−07, A8 =−4.85574E−09, A10 = 7.62677E−12

TABLE 6-1 (various data) Zooming ratio 4.19912 Wide Middle TelephotoFocal length 41.5596 88.1623 182.1306 F number 3.70547 4.32493 5.80463View angle 15.5868 7.0732 3.4237 Image height 11.0300 11.0300 11.0300Overall length of 111.2799 131.2672 153.1675 lens system BF 1.020551.02107 1.02173 d0 ∞ ∞ ∞ d5 1.4200 27.8703 40.9047 d9 14.2808 5.09961.7207 d14 9.1160 7.3403 1.4733 d24 20.8421 12.4878 1.9989 d26 1.53461.0433 1.8495 d28 19.9269 33.2659 61.0598

TABLE 6-2 (various data) Wide Middle Telephoto Focal length 41.181887.7556 174.5136 F number 3.70197 4.45073 6.19004 View angle 15.59826.8813 3.2215 Image height 11.0300 11.0300 11.0300 Overall length of111.2848 132.6071 156.5461 lens system BF 1.02549 3.87898 5.91833 d04000.0000 4000.0000 4000.0000 d5 1.4200 27.8703 40.9047 d9 14.28084.8789 1.5000 d14 9.1160 7.3403 1.4733 d24 21.0270 12.4890 2.6288 d261.3497 0.5243 0.7018 d28 19.9269 32.4864 60.2803

Numerical Example 3

The zoom lens system of Numerical Example 3 corresponds to Embodiment 3shown in FIG. 9. The data of the zoom lens system according to NumericalExample 3 is shown in the following tables.

TABLE 7 (surface data) Surface number r d nd vd Object surface ∞Variable  1 85.38600 1.20000 1.84666 23.8  2 56.20060 0.00000  356.20060 4.90350 1.49700 81.6  4 −380.01030 0.20310  5 43.12360 4.111401.48749 70.4  6 168.44930 Variable  7 245.63570 0.80090 1.90366 31.3  818.73670 2.18200  9 27.75070 2.27330 1.84666 23.8 10 −192.77500 Variable11 −43.66900 0.80290 1.83481 42.7 12 22.54310 0.10000 13 21.119401.47790 1.92286 20.9 14 44.96770 9.63640 15 ∞ Variable (Aperture) 16−2674.46190 1.99550 1.49700 81.6 17 −44.58500 4.02800 18 313.831801.75590 1.58913 61.3 19 −78.08120 0.62690 20 151.59040 2.14210 1.9228620.9 21 39.37540 1.41160 22 68.83710 2.71690 1.49700 81.6 23 −45.908200.20000 24 31.54750 2.71310 1.58913 61.3 25 −218.78510 Variable 26−2859.54900 0.89620 1.68966 53.0  27* 16.56320 0.58760 28 21.709901.30000 1.84666 23.8 29 34.36240 Variable 30 ∞ 4.20000 1.51680 64.2 31 ∞1.00000 32 ∞ 0.00136 Image surface ∞ 0.00000

TABLE 8 (aspherical data) Surface No. Parameters 27 K = 0.00000E+00, A4= −1.38925E−05, A6 = −7.94680E−08, A8 = 1.02088E−09, A10 = −1.01779E−11

TABLE 9-1 (various data) Zooming ratio 4.6504 Wide Middle TelephotoFocal length 41.3024 89.3487 192.9906 F number 3.59997 4.12017 5.80060View angle 15.3082 6.9550 3.2157 Image height 11.0300 11.0300 11.0300Overall length of 115.8306 135.4562 154.3771 lens system BF 0.001360.02021 0.08993 d0 ∞ ∞ ∞ d6 1.8818 28.9308 39.1703 d10 6.7906 2.06773.5347 d15 13.0171 8.8851 1.1406 d25 19.0991 12.5989 1.4100 d29 21.775429.6883 55.7664

TABLE 9-2 (various data) Wide Middle Telephoto Focal length 40.871786.0387 173.2193 F number 3.58892 4.09935 5.85658 View angle 15.36066.9970 3.1862 Image height 11.0300 11.0300 11.0300 Overall length of115.8257 135.4709 154.2672 lens system BF −0.00444 0.03492 −0.02593 d03884.1708 3864.5640 3845.7130 d6 1.8818 28.9308 39.1703 d10 6.79062.0677 3.5347 d15 13.0171 8.8851 1.1406 d25 19.3242 13.3291 2.9945 d2921.5512 28.9581 54.1878

Numerical Example 4

The zoom lens system of Numerical Example 4 corresponds to Embodiment 4shown in FIG. 13. The data of the zoom lens system according toNumerical Example 4 is shown in the following tables.

TABLE 10 (surface data) Surface number r d nd vd Object surface ∞Variable  1 78.42590 1.19980 1.87800 38.2  2 46.72820 6.00690 1.4970081.6  3 350.38430 0.19360  4 48.17050 5.84260 1.49700 81.4  5 1457.09620Variable  6 −201.19250 1.00000 1.75670 36.3  7 30.51420 9.30230  842.78680 2.10060 1.82027 29.7  9 −1708.73110 Variable 10 −45.942700.79990 1.75500 52.3 11 13.13030 2.22310 1.84666 23.9 12 37.491202.00070 13 ∞ Variable (Aperture) 14 258.91190 2.09420 1.59380 61.4 15−31.30260 0.19920 16 269.94740 4.08650 1.52540 70.5 17 −18.77030 0.799601.83918 23.9 18 −167.79930 Variable 19 −366.58870 3.09910 1.49700 81.620 −32.55030 0.20020 21 48.78510 2.47730 1.71852 33.5 22 −551.02540Variable 23 123.85260 0.77430 1.71371 54.5 24 27.80440 Variable 25 ∞4.19990 1.51680 64.2 26 ∞ 1.20462 Image surface ∞ 0.00000

TABLE 11-1 (various data) Zooming ratio 4.700 Wide Middle TelephotoFocal length 41.3304 89.7286 194.5268 F number 3.71919 5.10373 5.99992View angle 15.7997 6.9927 3.1902 Image height 11.0300 11.0300 11.0300Overall length of 135.1359 152.7756 171.2381 lens system BF 1.204621.24030 1.30620 d0 ∞ ∞ ∞ d5 2.4969 30.6249 41.5125 d9 17.1808 2.646513.0905 d13 14.3097 9.7475 1.4834 d18 9.5266 9.5266 9.5266 d22 24.008114.2184 2.0000 d24 17.8096 36.1716 53.7187

TABLE 11-2 (various data) Wide Middle Telephoto Focal length 41.158588.0536 178.8076 F number 3.72518 5.13555 6.16865 View angle 15.76916.9514 3.1059 Image height 11.0300 11.0300 11.0300 Overall length of135.1538 152.7643 171.3291 lens system BF 1.22216 1.22902 1.39756 d04000.0000 4000.0000 4000.0000 d5 2.4969 30.6249 41.5125 d9 17.18082.6465 13.0905 d13 14.3097 9.7475 1.4834 d18 9.3169 8.8948 7.5627 d2224.2179 14.8502 3.9640 d24 17.8096 36.1716 53.7186

Numerical Example 5

The zoom lens system of Numerical Example 5 corresponds to Embodiment 5shown in FIG. 17. The data of the zoom lens system according toNumerical Example 5 is shown in the following tables.

TABLE 12 (surface data) Surface number r d nd vd Object surface ∞Variable  1 82.85600 1.20000 1.84666 23.8  2 61.48560 9.13460 1.4970081.6  3 −2787.80860 0.20000  4 49.43870 6.71990 1.49700 81.6  5110.76750 Variable  6 30.95520 0.80000 1.88267 40.8  7 10.98510 5.70370 8* −62.02010 1.20000 1.85976 40.5  9 42.27070 0.10290 10 20.416002.80850 1.92286 20.9 11 126.26210 Variable 12 −79.87880 1.52840 1.9228620.9 13 −30.93440 0.59470 14 −18.98130 0.80000 1.88287 40.8 15 44.946701.35130 1.92286 20.9  16* 138.81620 Variable a 17 ∞ 1.50000 (Aperture)18 26.19950 1.98620 1.81231 45.2 19 −980.82960 0.10000 20 24.818602.05170 1.66588 58.4 21 −869.28790 2.59320 22 −45.80690 0.80000 1.9228620.9 23 46.31110 0.10000 24 30.60210 2.11400 1.49700 81.6 25 −54.372302.95370  26* 54.72500 0.80000 1.74728 51.2 27 31.33230 2.35990 1.5665069.0 28 −26.99190 Variable 29 −56.63870 1.33670 1.84666 23.8 30−28.85260 0.80000 1.81159 45.3  31* 109.74970 Variable 32 77.539902.08690 1.62538 35.6 33 −38.55300 0.89750 34 −17.33640 0.80000 1.8828940.8 35 −68.31790 0.10000 36 41.63170 1.65490 1.65233 32.6 37 214.46340Variable 38 ∞ 4.20000 1.51680 64.2 39 ∞ BF Image surface ∞

TABLE 13 (aspherical data) Surface No. Parameters 8 K = 0.00000E+00, A4= −1.55711E−05, A6 = 5.12022E−08, A8 = −2.29523E−09, A10 = 1.12839E−1116 K = 0.00000E+00, A4 = −1.02230E−05, A6 = 2.34863E−08, A8 =−1.21507E−09, A10 = 2.21100E−11 26 K = 0.00000E+00, A4 = −6.08663E−05,A6 = −1.02979E−07, A8 = −1.95916E−10, A10 = 6.57580E−12 31 K =0.00000E+00, A4 = −1.20760E−05, A6 = −2.63940E−07, A8 = 7.32088E−09, A10= −8.30305E−11

TABLE 14-1 (various data) Zooming ratio 9.39665 Wide Middle TelephotoFocal length 14.4195 45.8042 145.4801 F number 3.60057 4.19379 5.80043View angle 40.4346 13.5612 4.2125 Image height 11.0300 11.0300 11.0300Overall length of 100.6138 130.7860 164.5049 lens system BF 1.006761.07461 0.98186 d0 ∞ ∞ ∞ d5 1.0000 30.6930 56.5691 d11 3.7603 2.86582.0000 d16 15.1769 4.8771 1.5000 d28 2.0675 7.3071 1.0000 d31 5.05032.6335 15.6147 d37 11.1733 19.9562 25.4605

TABLE 14-2 (various data) Wide Middle Telephoto Focal length 14.401345.3347 135.4949 F number 3.60094 4.20803 5.85992 View angle 40.508013.5842 4.1940 Image height 11.0300 11.0300 11.0300 Overall length of100.6170 130.8113 164.4475 lens system BF 1.00193 1.09928 0.95442 d03884.0557 3864.6948 3845.7762 d5 1.0000 30.6930 56.5691 d11 3.76032.8658 2.0000 d16 15.1769 4.8771 1.5000 d28 2.1059 7.5949 2.6531 d315.0200 2.3463 13.9317 d37 11.1733 19.9562 25.4605

The following Tables show values corresponding to the individualconditions in the zoom lens systems of the numerical examples.

TABLE 15 (corresponding values to individual conditions: NumericalExamples 1 to 3) Numerical Example Condition 1 2 3 (1) |f_(F)/f_(of)|0.577 0.674 0.860 (2) |f_(O)/f_(W)| 0.800 0.756 0.730 (3) |f₂/f₁| 2.0840.883 2.166

TABLE 16 (corresponding values to individual conditions: NumericalExamples 4 and 5) Numerical Example Condition 4 5 (1) |f_(F)/f_(of)|1.279 2.490 (2) |f_(O)/f_(W)| 0.747 2.051 (3) |f₂/f₁| 3.120 0.229

The zoom lens system according to the present invention is applicable toa digital input device such as a digital still camera, a digital videocamera, a mobile telephone, a PDA (Personal Digital Assistance), asurveillance camera in a surveillance system, a Web camera or avehicle-mounted camera. In particular, the present zoom lens system issuitable for an imaging device in a digital still camera, a digitalvideo camera or the like that requires high image quality.

Details of the present invention have been described above. However, theabove-mentioned description is completely illustrative from every pointof view, and does not limit the scope of the present invention.Obviously, various improvements and modifications can be performedwithout departing from the scope of the present invention.

1. A zoom lens system, in order from an object side to an image side,comprising: a first lens unit having positive optical power; a secondlens unit having negative optical power; a third lens unit havingnegative optical power; a fourth lens unit; and a fifth lens unit,wherein at the time of zooming, all lens units move in a direction alongan optical axis so that intervals between the lens units vary, at thetime of focusing, either a part of the fifth lens unit or an entirety ofthe fifth lens unit is a focusing lens unit and moves in a directionalong the optical axis, and the focusing lens unit has negative opticalpower, wherein the third lens unit is an image blur compensation lensunit and moves in a direction perpendicular to the optical axis at thetime of compensating image blur caused by vibration in the zoom lenssystem, and the zoom lens system satisfies the following condition:0.5<|f _(o) /f _(W)|<2.8  (2)f _(T) /f _(W)>4 where, f_(o) is a focal length of the image blurcompensation lens unit, f_(T) is a focal length of the zoom lens systemat a telephoto limit, and f_(W) is a focal length of the zoom lenssystem at a wide-angle limit.
 2. The zoom lens system as claimed inclaim 1, satisfying the following condition:0.3<|f _(F) /f _(of)|<6.0  (1) where, f_(F) is a focal length of thefocusing lens unit, and f_(of) is a composite focal length of the lensunits located within a range from the image blur compensation lens unitto the focusing lens unit at a wide-angle limit.
 3. The zoom lens systemas claimed in claim 1, satisfying the following condition:0.1<|f ₂ /f ₁|<3.5  (3) where, f₁ is a focal length of the first lensunit, and f₂ is a focal length of the second lens unit.
 4. Aninterchangeable lens apparatus comprising: a zoom lens system; and acamera mount section connected to a camera body provided with an imagesensor for receiving an optical image formed by the zoom lens system andthen converting the optical image into an electric image signal, whereinthe zoom lens system, in order from an object side to an image side,comprises: a first lens unit having positive optical power; a secondlens unit having negative optical power; a third lens unit havingnegative optical power; a fourth lens unit; and a fifth lens unit,wherein at the time of zooming, all lens units move in a direction alongan optical axis so that intervals between the lens units vary, at thetime of focusing, either a part of the fifth lens unit or an entirety ofthe fifth lens unit is a focusing lens unit and moves in a directionalong the optical axis, and the focusing lens unit has negative opticalpower, wherein the third lens unit is an image blur compensation lensunit and moves in a direction perpendicular to the optical axis at thetime of compensating image blur caused by vibration in the zoom lenssystem, and the zoom lens system satisfies the following condition:0.5<|f _(o) /f _(W)|<2.8  (2)f _(T) /f _(W)>4 where, f_(o) is a focal length of the image blurcompensation lens unit, f_(T) is a focal length of the zoom lens systemat a telephoto limit, and f_(W) is a focal length of the zoom lenssystem at a wide-angle limit.
 5. A camera system comprising: aninterchangeable lens apparatus that includes a zoom lens system; and acamera body that is connected to the interchangeable lens apparatus viaa camera mount section in an attachable and detachable manner and thatincludes an image sensor for receiving an optical image formed by thezoom lens system and then converting the optical image into an electricimage signal, wherein the zoom lens system, in order from an object sideto an image side, comprises: a first lens unit having positive opticalpower; a second lens unit having negative optical power; a third lensunit having negative optical power; a fourth lens unit; and a fifth lensunit, wherein at the time of zooming, all lens units move in a directionalong an optical axis so that intervals between the lens units vary, atthe time of focusing, either a part of the fifth lens unit or anentirety of the fifth lens unit is a focusing lens unit and moves in adirection along the optical axis, and the focusing lens unit hasnegative optical power, wherein the third lens unit is an image blurcompensation lens unit and moves in a direction perpendicular to theoptical axis at the time of compensating image blur caused by vibrationin the zoom lens system, and the zoom lens system satisfies thefollowing condition:0.5<|f _(o) /f _(W)|<2.8  (2)f _(T) /f _(W)>4 where, f_(o) is a focal length of the image blurcompensation lens unit, f_(T) is a focal length of the zoom lens systemat a telephoto limit, and f_(W) is a focal length of the zoom lenssystem at a wide-angle limit.